#define _CRT_SECURE_NO_WARNINGS 1
#include<stdbool.h>
bool _isSymmetric(struct TreeNode* p, struct TreeNode* q)
{
    if (p == NULL || q == NULL)
    {
        return p == q;
    }
    return p->val == q->val && _isSymmetric(p->left, q->right) && _isSymmetric(p->right, q->left);
}
bool isSymmetric(struct TreeNode* root) {
    return _isSymmetric(root->left, root->right);
}